The present invention relates to washers used for scrubbing the surfaces of substrates used in the production of recording media, and in particular to washers that use pads and/or brushes.
During the manufacture of recording media, such as magnetic or magnetic-optical disk, at least one cleaning step is performed. Typically, a brush (or pad) material is attached to a cylindrical roller that is pressed against the substrate surface. The brush is rotated and pressed against the substrate surface to scrub the disk. Typically, two rollers are used and pressed against opposite side of the substrate so that both surfaces are scrubbed simultaneously and no net pressure is applied to the disk, which could damage or break the disk.
FIGS. 1 and 2 show front and side views, respectively, of a conventional washer 10 cleaning a disk 12. Washer 10 includes two scrubbing rollers 14, 16 (roller 16 is hidden from view in FIG. 1) which are rotated as shown by arrow 15 in FIG. 1 and arrows 17 and 18 in FIG. 2. Scrubbing rollers 14 and 16 can be moved toward and away from the disk 12, as indicated by arrows 20 and 22, so that disk 12 may be easily loaded and unloaded. Washer 10 also includes driving rollers 24, 26 (roller 26 is hidden from view in FIG. 2), which contact the outside diameter of disk 12. Driving rollers 24, 26 are rotated, as indicated by arrows 25, 27 in FIG. 1 and arrow 28 in FIG. 2, to rotate disk 12 as indicated by arrow 13. A lift arm 30 is used to lift disk 12 into washer 10.
During operation, lift arm 26 lifts disk 12 into washer 10 and between scrubbing rollers 14 and 16, which are separated to allow disk to be lifted between them. Scrubbing rollers 14 and 16 are pressed against disk 12 and rotate as indicated by arrows 17 and 18 in FIG. 2. The rotation of scrubbing rollers 14 and 16 pushes disk 12 upwards against driving rollers 24 and 26. The rotation of driving rollers 24 and 26 causes disk 12 to rotate as indicated by arrow 13. Thus, as disk 12 rotates, scrubbing rollers 14 and 16 rotate and simultaneously scrub both sides of disk 12. Once disk 12 has been scrubbed driving rollers 24 and 26 stop, lift arm 30 raises to disk 12 and scrubbing rollers 14 and 16 separate. Lift arm 30 then lowers disk 12 from washer 10.
While a conventional washer, such as washer 10, operates adequately with large form factor disks, such as 95 mm disks, washer 10 has two key deficiencies when used to wash small form factor disks, such as one-inch disks. The first deficiency is caused by the edge of small form factor disks being sharper than larger form factor disks. The sharp edge of small form factor disks can cut into the driving rollers 24 and 26, particularly if there is any slippage between driving rollers 24 and 26 and the outside diameter of the disk. Cutting into driving rollers 24 and 26 can lead to contamination of the disk and undue wear on the driving rollers.
The second deficiency that occurs when washer 10 is used with small form factor disks occurs during insertion and removal of the disk from between the scrubbing rollers 14 and 16. Because small form factor disks have little weight, the disks tend to stick to the scrubbing rollers 14 and 16 from surface tension. Consequently, loading and unloading small form factor disks from washer 10 is problematic.
A washer in accordance with an embodiment of the present invention uses two sets of rollers that are aligned along two different radii of a disk separated by 180 degrees. One set of rollers drives the rotation of the substrate while the other set of rollers scrubs the surfaces of the substrate. A set of outside diameter rollers, which are free spinning in one embodiment, are positioned to contact the outside diameter of the disk during the scrub cycle. With the outside diameter rollers free spinning, there is no slippage between the disk and the rollers, consequently the disk does not cut into the rollers. In another embodiment, the outside diameter rollers are rotated at the same speed as the outside diameter of the disk. In addition, the rotation of the driving and scrubbing rollers is used to pull the disk into the loaded position. The rotation of the driving and scrubbing rollers can be reversed to unload the disk. In another embodiment, the rotation of the driving and scrubbing rollers continues in the same direction and the outside diameter rollers separate to unload the disk. Because the driving and scrubbing rollers are not separated during loading and unloading, the disk is forced into and out of the scrub position and thus, the disk will not stick to the rollers.
Thus, in accordance with one embodiment of the present invention, an apparatus for washing substrates, such as small form factor disks, includes a first set of rollers including a first roller and a second roller each having an axis of rotation, the first roller axis and the second roller axis being perpendicular. The first and second rollers being on opposite sides of a substrate when a substrate is loaded. The washer also includes a second set of rollers including a third roller and a fourth roller, each having an axis of rotation, the third roller axis and fourth roller axis being perpendicular. The third and fourth rollers being on opposite sides of a substrate when a substrate is loaded. The washer also includes at least one outside diameter roller that is free spinning and that has an axis of rotation that is perpendicular to the axis of the first roller. The outside diameter roller is positioned to be in contact with the outside diameter of the substrate when a substrate is loaded. The rollers may have a brush material or a pad material attached. At least one motor is coupled to the first and second roller and at least one more motor is coupled to the third and fourth rollers.
The first set of rollers and second set of rollers may be positioned such that when a substrate is loaded between the rollers, the first set of rollers extend approximately along a first radius and the second set of rollers extend approximately along a second radius of the substrate, where the first radius is 180 degrees apart from the second radius. In addition, the first set of rollers and the second set of rollers extend from approximately the center of the substrate to past the outside diameter of the substrate so that the entire substrate can be washed. The first set of rollers and second set of rollers may be mounted on holders that are adjustable to increase or decrease the pressure that is applied to the substrate. In addition, the speed of rotation of the first set of rollers and the second set of rollers may be altered.
The washer also includes a lift arm that is positioned to lift a substrate to the first set and second set of rollers. The lift arm includes a xe2x80x9cVxe2x80x9d shaped groove in which a substrate may sit. The lift arm also includes a notch at the base of the xe2x80x9cVxe2x80x9d shaped groove, which is used to ensure that the substrate is held vertically when the substrate is loaded between the first set and second set of rollers.
In accordance with another embodiment of the present invention, a method of washing a substrate includes rotating a first pair of rollers in opposite directions, rotating a second pair of rollers in opposite directions, loading a substrate between the first pair of rollers and between the second pair of rollers, wherein the first pair of rollers presses against opposing surfaces of the substrate and the second pair of rollers also presses against the opposing surfaces of the substrate, rotating the substrate in the plane of the substrate with the first pair of rollers, and scrubbing the opposing surfaces of the substrate with the second pair of rollers. Loading the substrate includes lifting the substrate to the first pair of rollers and to the second pair of rollers; and pulling the substrate into position between the first pair of rollers and between the second pair of rollers with the outside diameter of the substrate pressed against at least one free spinning roller, wherein the rotation of the first pair of rollers and of the second pair of rollers pulls the substrate into position. Unloading the substrate includes pushing the substrate from between the first pair of rollers and between the second pair of rollers by reversing the direction of rotation of the first pair of rollers and of the second pair of rollers, and lowering the substrate from the first pair of rollers and from the second pair of rollers. In another embodiment, unloading the substrate includes separating at least two free spinning rollers that are in contact with the outside diameter of the substrate while continuing to rotate the first pair of rollers and continuing to rotate the second pair of rollers.
The method of washing a substrate also includes controlling the rate of rotation of the substrate, by adjusting the pressure on the substrate applied by at least one of the first pair of rollers and the second pair of rollers, or by altering the rate of rotation of at least one of the first pair of rollers and the second pair of rollers.